How this calculator works
A three-part ratio compares quantities A, B and C together. Their decimal spellings are aligned to a common power of ten before a greatest common divisor reduces them to integer terms. Shares use each original term divided by the sum. Multiplying or dividing every term preserves the proportions; normalising a selected non-zero term makes that term one. Numeric inputs retain about 15 to 17 significant digits.
Formula
Share A = total × A/(A + B + C), and likewise for B and C. An equivalent ratio is kA:kB:kC for k > 0.
Worked example
The ratio 6:9:15 reduces to 2:3:5. Sharing 100 gives 20, 30 and 50. The decimal ratio 0.5:0.75:1 reduces to 2:3:4, so a total of 90 divides into 20, 30 and 40.
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Frequently asked questions
Can a term be zero?
Yes, provided another term is positive. The zero part receives no share and cannot be chosen as the term to normalise to one.
Can I mix units?
Convert comparable quantities to the same unit first. For a recipe with different ingredients, use a consistent convention such as mass parts throughout.
Why might displayed shares add up slightly differently?
Each displayed number is rounded separately. The calculations use full precision, and fractional shares such as one third do not have a finite decimal expansion.